Balanced, probe-fed, micro-strip patches have good broadband properties when operated in antenna arrays. Such elements 1 require two probes per polarisation, implying four probes 3 for a doubly polarised element, also see FIGS. 1a and 1b defining prior art.
Self-complementary antenna elements are known to possess a fix input impedance (half the intrinsic impedance of space, Z0/2≈188.5 ohms) over a wide bandwidth. The theory of the self-complementary antenna was established already 1949 by the Japanese Professor Mushiake.
Micro-strip patch technology offers the possibility of fabricating a large number of antenna elements in one, cheap process step with small tolerances. Antenna arrays in triangular, or rather, hexagonal grids are considered optimal since they offer efficient packaging and avoid grating lobes.
Balanced probe fed micro-strip patch antennas previously have been realised with two probes per polarisation as illustrated in FIG. 1. For instance the U.S. Pat. No. 6,597,316 B2 discloses a spatial null steering micro-strip antenna array where each antenna element is appropriately excited by symmetrically spaced probes. Another U.S. Pat. No. 5,229,777 discloses a micro-strip antenna having a pair of identical triangular patches maintained upon a ground plane, with feed pins being connected to conductive planes of the triangular patches at apexes maintained in juxtapositions to each other. The input signals to the pair of patches are of equal amplitude, but 180° out of phase.
The authors presume that also three-phase feeding would have been generally proposed in the literature. An equidistant phase (120 degrees) between such probes yields so-called circular polarisation.
Self-complementary antennas are currently considered for broadband systems. Most often realised in micro-strip technology, their conducting topology is identical with its non-conductive if mirrored, translated and/or rotated. The advantages of micro-strip patch antenna arrays are well known, so are those of hexagonal arrays.
However a micro-strip patch design of a self-complementary probe-fed antenna element in a hexagonal array configuration transmitting/receiving arbitrarily polarised RF radiation with co-located phase centres of each polarisation has not been disclosed previously. Hence the defined problem is then solved by the present invention.